This page shows distortion at 16mm and comments on how much is lost to distortion correction, showing the effects with various crops at various resolutions.

It is noteworthy that with decades of history of including distortion graphs in data sheets, Leica does not include a distortion graph in the data sheet for the Leica 16-35mm f/3.5-4.5 Super-Vario-Elmar-SL ASPH (ditto for other SL lenses). Nor does Leica supply MTF charts that are measured with a real lens, nor do the computed for distortion correction losses in contrast.